


Cheat Day

by Tsukimi11



Category: Toaru Majutsu no Index | A Certain Magical Index
Genre: Canon Compliant, Comedy, Fluff and Crack, Gen
Language: English
Status: Completed
Published: 2020-08-13
Updated: 2020-08-13
Packaged: 2021-03-06 06:54:31
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,740
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25879252
Author URL: https://archiveofourown.org/users/Tsukimi11/pseuds/Tsukimi11
Summary: Last Order and Index accidentally swap bodies, which leads to Accelerator to despair trying to fix things, Touma to cry tears of happiness because Last Order-in-Index doesn't bite him, and the Sisters to wreck havoc in Academy City.
Relationships: Accelerator & Kamijou Touma, Accelerator & Last Order (A Certain Magical Index), Kamijou Touma & Index
Comments: 4
Kudos: 36





	Cheat Day

**Author's Note:**

  * For [KaguraKurosaki](https://archiveofourown.org/gifts?recipient=KaguraKurosaki).



> Happy Birthday Kagu! 
> 
> I remembered we jokingly discussed this idea months ago so I decided to make it a fic, hope it makes you laugh in this special day!

When Accelerator woke up one morning by himself, he immediately discovered that something was very wrong.

Usually he would be woken up very early by an unknown ball of energy that liked to pounce on him demanding his immediate attention and be dragged out of bed for who-knows-what. Usually food, because Last Order insisted they eat every meal together because ‘family always eats together.’

Accelerator had huffed at that at first, but they had eaten together every time they could ever since.

But that morning Accelerator didn’t get shaken to be woken up and no one was jumping on him, which was concerning, so he quickly got up and headed to the living room, convinced that the brat would be hiding somewhere to jump on him as her daily prank.

No one was in the living room.

He frowned and was about to check every space that could serve as a hiding spot when he heard noises from the dining area and, curious, he went to see what those sounds were, freezing at the scene in front of him.

Accelerator stared dumbfounded as Last Order wolfed down a bowl of rice in record time and devoured all the side dishes that had been in the fridge and that were supposed to last them the whole week. She didn’t even acknowledge his presence, when normally she would always smile at him and make sure to annoy him with whatever random fact she had discovered recently.

The girl in front of him, however, was too engrossed eating her heart out that Accelerator worried she might choke, given that she wasn’t even pausing to breathe.

Did Last Order even eat that much? Was she so suddenly ill that she needed to replenish her body by eating nutrients non-stop? Or was she so mad that he had rejected her idea to play house last night that she had decided to act spiteful and eat even his share of food?

No, that was ridiculous. Last Order wouldn’t do something so childish — despite the fact that she was indeed a child.

He opened and closed his mouth trying to say something but didn’t know what to say, and he must have made a sound as Last Order finally noticed his presence, scratching the back of her head and giving him a sheepish smile.

“Sorry, I was too hungry and couldn’t resist when I saw all this food available! This is so good, I could eat this for days!”

And with that, she hopped off her seat to serve herself another bowl of rice from one of the many rice cookers lining up the kitchen, and Accelerator noted with a grimace that at least three were on and cooking rice at the moment.

He still didn’t understand what was going on, but one thing was for sure: the brat in front of him wasn’t Last Order. She didn’t talk like she usually did and wasn’t using all her energy to annoy him to no end, plus, she was casually ignoring him while stuffing her face with food. And he had been sure to teach her manners when eating, which certainly didn’t include eating so ravenously and in such large quantities.

Still confused, he marched up to her and stopped her from leaving with her bowl full of rice by blocking her way to the dining table.

“Who are you and what have you done to Last Order?”

Last Order had frowned when Accelerator cut her off, but then she blinked and tilted her head in confusion.

“What do you mean? Last Order? My name is Index. We’ve met before, don’t you remember me?”

Now it was Accelerator’s turn to blink in confusion, not understanding the words that he had just heard. Index? The brat wearing nun clothes that was always clinging to Kamijou Touma? 

Her eyes widened and she frowned in irritation.

“Did you already forget about me? How can you forget such a pretty lady like me? I’m pretty sure I’m unforgettable!”

He sighed, part in irritation and part in confusion. Didn’t she realize that she was not in her body? Had she just gotten up and gone straight to eat, without looking at herself in a mirror? 

To not waste time, he took the bowl of rice from her hands and took her to the bathroom, the brat complaining in confusion all the time, but she shut up pretty quickly when Accelerator pointed at the mirror and she finally saw her reflection.

Her eyes widened in panic and she started touching her face, as if checking if she was really the person that was reflected on the mirror before touching the mirror itself in her confusion.

Accelerator watched the whole scene unfold in front of him, before she turned to him with teary eyes.

“What’s going on? Why am I in this body?”

Accelerator scratched the back of his head, not sure himself. Instead of replying a question he could not answer, he took his phone out of his pocket and called the only person who could maybe help him and answer his own questions.

“Hello?”

“It’s me. Is your brat over there acting weird?” Accelerator went straight to the point, hoping that Last Order was indeed where he thought she was.

“Index? Yeah, how did you know?”

“Apparently our brats changed their bodies when we were all sleeping and Index is now in Last Order’s body.”   
“Really!? Is that why Index had been calling herself Misaka all this time? So now Index is actually Misaka’s sister’s sister?”

“Wait, is that Touma?” Last Order — or Index, more precisely — asked, and tried to get the phone which Accelerator easily stopped her from doing, as she was quite short.

“Yeah, so keep quiet while we try to figure out what’s going on,” he answered her curtly, hoping to shut her up. “Kamijou Touma, I will ask someone I know if they have an explanation for this. You just keep that brat inside your place, got it?”

“Sure, but you also keep Index safe, okay?”

“Who do you think you are talking to?” Accelerator huffed. “I’ll stop by your place with your brat in the afternoon, so please try not to start a war in the meantime.”

“Hey!”

Accelerator hung up and sighed: it was way too early for something weird like this. Index was pouting at him and he was surprised she hadn’t started biting him — something that Kamijou Touma was always suffering from — and he pinched the bridge of his nose to prevent a headache from ruining his day.

“We’re going to see a doctor I know, but let’s finish having breakfast first.”

Index perked up and quickly dashed to the dining room with a happy expression, Accelerator following after her to at least get a cup of coffee before he ended up killing someone by accident.

It was really too early for this, he thought while he saw Index eating the whole contents of a rice cooker in record time and made a mental note to go to the supermarket soon to replenish their now-empty fridge.

* * *

“There’s nothing wrong with her,” the frog doctor checked his notes and studied Index, who was munching on some candies. “Physically, at least. I would say that this is temporary and she will be back into her own body by tomorrow morning.”

“Are you sure about that?” Accelerator was skeptical, not wanting to risk the chance of learning later that this was indeed a serious condition. He wouldn’t forgive himself if something happened to Last Order.

“I can’t say for sure, but that is my opinion as a doctor in this strange city,” the doctor put his notes down. “I will ask for some more exams, but I think that there’s nothing to worry about.”

Accelerator bit his tongue, his guts screaming at him that he was forgetting something important and that disaster would follow them along the road. And Kamijou Touma was involved in this somehow as well, so there were high chances of this becoming a catastrophe later on.

And still, how and why did Last Order’s and Index’s bodies get exchanged? They hadn’t been in contact for a while now, so how? Last night had been pretty normal as well, and he was sure that there was nothing wrong with their food or drinks because he would have been affected as well in that case. 

Accelerator sighed, not understanding what was going on. He left the examination room to get another coffee to clear his mind, but he froze when he saw two Sisters running through the halls: one was running away while eating bread and the one behind her was apparently chasing after her with a semi-automatic rifle.

“Stop right there, orders Misaka 10032 as she tries to aim at 13577 for the betrayal 10032 has suffered.”

“Misaka needs to run as she feels a risk on her life for the inexplicable urge to eat as much as she can, explains Misaka 13577 while she escapes from the other Misakas.”

“The need is shared and that bread needs to be rationed between all Misakas, counters Misaka 10032 while she tries to capture 13577.”

And with that, they ran around the corner where they disappeared from Accelerator’s sight, who froze with horror at what he had seen.

The Sisters were fighting each other over food, going as far as to use weapons on each other in a hospital. It should have been a funny scene, but he remembered that now Index was in Last Order’s body so she might have control over the Misaka Network, and that brat likely hadn’t stopped eating since she got up in the morning. 

Accelerator gasped loudly at his realization and barged back into the examination room, where Index was indeed munching on a bread that most likely the frog doctor had given her. 

“What’s wrong? You seem like you saw a ghost,” the frog doctor asked, worry evident in his voice. Accelerator could only raise a shaky finger towards Index.

“You! Do you have any type of control over the network now!?”

Index swallowed down and blinked in confusion.

“What network? But yeah, I’ve been hearing voices in my head although I’m used to hearing things, so I’m okay!”

“That’s not the problem!” Accelerator wanted to pull his hair out. “The problem is that the Sisters are being influenced by you!”

“Ah,” the doctor made a face, and he quickly called someone on his phone.

“I don’t understand why you are so mad, I’ve done nothing wrong!” Index pouted, and she finished her bread despite Accelerator’s glares.

As much as he wanted to take that piece of bread from her hands and just tie her up so she wouldn’t be eating any more, she knew that Kamijou Touma wouldn’t forgive her if something happened to Index, not to mention that it wouldn’t stop the Sisters from killing each other over food.

“Well, it seems like the Sisters are okay, just very hungry,” the frog doctor finished his call. “I think this is a side effect of the body swap, but it should be harmless. Don’t worry too much about it and just try to keep both kids safe. Just come see me tomorrow if they are not back in their bodies.”

Index hopped off her chair, a satisfied smile in her face.

“We’re done, right? Let’s go see Touma! I’m sure he’s worried about me, I need to let him know I’m okay!”

Accelerator groaned and hoped that the Sisters fighting to death over food would be the least of his problems, even though his guts told him that this was far from over.

* * *

“Oh, isn’t that nice, Last Order? You will be back to your bodies by tomorrow and everything will be solved!” Kamijou Touma smiled at Last-Order-in-Index, who smiled back at him.

“Misaka needs to take care of that person, so Misaka is happy that Misaka will be able to make sure that he eats healthy tomorrow, says Misaka happily as Misaka jumps into Accelerator’s arms!”

“Why are you so calm about this situation!?” Accelerator caught Last Order in his arms and put a hand around her to stop her from moving away from him. “The Sisters are out of control!”

“They are just living their teenage lives, you don’t need to worry about them,” Index dismissed his worries while trying to coax Sphinx out of under the bed — most likely the cat didn’t recognize her in her new body and stayed put, which could be a nice idea.

“They bought all the products of a bakery and were fighting over cakes!”

“You don’t understand a lady’s heart, do you?” Index gave her a look full of pity. “We need sweets in our lives, and cakes just upgrade our ladyness, so it’s okay!”

“No, it’s not! They almost destroyed the bakery in their fight!”

“You’re just exaggerating, that stuff is normal for teenage girls,” Index rolled her eyes.

Kamijou Touma gave him a sheepish smile at Index’s attitude and Last Order squirmed under him.

“Misaka also wants some cake, pleads Misaka as Misaka asks for a reward for her nice behaviour today!”

“I doubt there’s any place open in the Academy City with cakes left by now,” Accelerator mumbled, irritated that he was the only one finding the situation weird.

He just couldn’t get the image of the Sisters raiding a bakery while he had been unable to do anything, trapped inside a car towards Kamijou Touma’s house — the stupid taxi driver had refused to stop or make a detour. But he swore he saw them wolfing down the cakes aggressively and fighting over them, and he just worried about all the remaining Sisters all over the world attacking people over food.

“As you just said, this will last only a day, right? One day they spend eating treats would do no one harm!” Kamijou Touma tried to calm him down, but that only made him worry more.

“What if one of the Sisters decides she is still hungry and attacks someone with food? They could be killed by the Anti-Skills!”

“The Sisters aren’t that stupid, they won’t do that,” Kamijou Touma chuckled nervously at the intensity of Accelerator’s worries.

“You can’t know, I saw one of them chasing another one with a rifle over a bread!”

“Those Misakas are quite problematic, agrees Misaka as Misaka nods her head and folds her arms like an adult.”

“By the way, what are we going to do with Index and Last Order?” asked Kamijou Touma despite Accelerator’s glare at his attempt to change the topic. “I mean, you’re used to Last Order but she’s in Index’s body, so it makes sense that you want to take Index’s body to your place. But when they wake up tomorrow, we will have to swap them again, so maybe Index-in-Last Order should go home with you?”

“Huh?” Accelerator felt another problem worsening his headache. “Of course I’m taking Last Order back with me, no matter the body she’s in.”

“Oh please,” Kamijou Touma pleaded. “Take Index’s mind back with you, it’ll be less of a problem in the future.”

“I don’t mind coming back tomorrow.”

“Okay, just let me say it this way,” Kamijou Touma stood up from where he had been sitting on the floor and gave Accelerator a determined stare. “Last Order is easier to take care of, so please let me have one day where I don’t feel like a slave in my own house.”

“HUH!?” Index popped her head out from under the bed and stomped her way towards Kamijou Touma. “What do you mean by  _ that _ !?”

“Well, Last Order helped me cook and she is so sweet, she doesn’t demand me to give her all my food and — ”

Index jumped on Kamijou Touma and started biting his head off while punching him, making him unable to continue as he was busy now screaming in pain and asking for forgiveness.

“That sure was violent, comments Misaka as Misaka thinks it is unnecessary that Misaka’s eyes are covered for this.”

“Just shut up and forget what just happened,” replied Accelerator while he covered Last Order’s eyes, not impressed by the behaviour of Index in front of him but surely intimidated by the sight of Last Order’s small body biting Kamijou Touma, and grateful that the real Last Order didn’t have a thing for attacking people with her teeth.

“SUCH MISFORTUNE!!!”

**Author's Note:**

> At the end of the day the Sisters ate so much they despaired horribly the next day, since they had to start dieting to Last Order's laughter lol


End file.
